Electrical control circuit



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P. GLASS ELECTRI CAL CONTROL CIRCUIT Nov.9, 1948.

Filed Feb. 2a, 1945 w N SMN fl|+||l I III:

N ME

Nov. 9, 1948. P. GLASS ELECTRICAL CONTROL CIRCUIT 2 Sheets-Sheet 2 Fneu eb. 28, 1945 C ay/ am I Patented Nov. 9,1948

ELECTRICAL CONTROL CIRCUIT Paul Glass, Chicago, Ill., assignor to Askania Regulator Company, Chicago, 111., a corporation of Illinois Application February 28, 1945, Serial No. 580,261 12 Claims. (01.175483) The invention relates generally to electrical control circuits and more particularly to control circuits wherein a small signal is utilized to govern substantially larger power applications, or,

where the signal is amplified or modified, or both, for subsequent use in its amplified and/or modified form.

Heretoiore circuits of the character described have depended largely upon electron tubes for accomplishment of the ends sought, necessitating complicated circuits or excessive numbers of stages of amplification with the resultant disadvantages of high cost, operational and maintenance diificulties and, above all, the disadvantage that the controlling portion' of the circuit was not completely independent of the controlled portion so that reaction in the controlled portion .might reflect into the controlling portion with possible resultant injury thereto.

It is an object of this invention, therefore, to provide'new' and improved circuits for the amplificationor modification, or both, of a signal, or for the utilization of a small signal in the control of substantially larger power applications.

Another object of the invention is to provide new and improved electrical control circuits adaptable. to respond either to alternating current or' direct current signals and adaptable to V produce either direct or alternating current.

Another object is to provide new and improved electrical control circuits in which the input or controlling circuit is completely separated electrically from the output or controlled circuit and cannot be influenced by the output circuit.

) Another object is to provide a circuit of the character described having a portion operating function as a stable and linear alternating current power amplifier, or as a linear amplifier and converter of A. C. signals to direct current.

Other objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Fig. l is'a box-type diagrammatic illustration of a circuit embodying the ieatures of this invention.

Fig. 2 is a circuit diagram illustrating in detail a possible construction that the units represented.

by the rectangles in Fig. 1 may take.

Fig. 3 is a diagram illustrating. the character or the output of the. first unit of the circuit.

Fig. 4 is a diagram similar to Fig. 3 illustrating the character of the output of the second unit of the circuit. Fig. 5 is a diagram similar to Fig. 3 illustrating the character of the final output of the circuit. Fig. 6 is a box-type circuit diagram showing a modified embodiment of the invention.

' Fig. 7 is a circuit diagram illustrating a specific form that the units represented by the rectangles of Fig. 6 may take.

Fig. 8 is a circuit diagram illustrating another specific form that the'units represented by the rectangles of Fig. 1' may take.

Fig. 9 is a diagram illustrating the character of the output of the first unit of Fig. 8.

Fig. 10 is a diagram similar to Fig. 9 illustrating the character of the output of the second unit of Fig. 8.

as a large range amplification stage which is 1 without electron tubes.

Another object is to provide a circuit of the character described having an electron'tubeless, main amplification or control stage and an input signal circuit in advance of the main stage conditioning the signal by modification and possibly also amplification for use in connection with the main stage.

Still another object is to provide a control circuit in which the main amplification and control means is composed of saturable reactors.

A further object is to provide a control circuit including saturable reactors which will function as a stable and linear direct current power am- .Still a further object is to provide a control til-cult including saturable reactors which will Fig. 11 is adiagram similar to Fig. 9-illustratv ing the character of the output of the third or final unit of Fig. 8.

For purposes of disclosure there is shown in l the drawings and will hereinafter be described a general and several specific circuits, being illustrative embodiments of the invention. It is not intended, however, that the invention is to be limited thereby to the specific disclosures made. On the contrary. it is intended to cover all modifications and alternative constructions falling within the spirit and scope of the invention as defined in the appended claims.

Generally speaking, the invention contemplates the provision of a new and improved circuit wherein a small electrical signal is utilized to govern substantially larger power applications or where the signal isamplified or modified, possibly both, for subsequent use in its new term. In such a circuit the input is a controlling signal while the output is a controlled signal regardless of whether the latter is of a magnitude commonly 4 referredgto a signal 'an elect as .to be" 11 the controlling or the controlled signal, and

means functioning as the main control means.

Herein the general circuit (see Fig. l) is composed of three subcircuits or circuit units or portions A, B and C. Of these units, A is the main amplifying or control means or circuit and functions to' have an output of alternating current controlled as to magnitude and sign by the controlling or input signal, but having an independent power source so'that the power output is not limited by the power of the signal source. Unit B is the control signal receiving unit. This unit usually functions to amplify the signal but, above all, it modifies the character of the signal so as first to obtain a signal of a character suitable for use with unit A, and, secondly, toobtain amplifying or a signal of'such character as to result in an output of a character desired. Unit C is also a modifier of the signal which it receives, though herein the function of unit C is always that of a rectifier converting the A, C. output of unit A to a D. C. output. Theterm direct current or its abbreviation D. C.', as herein employed to designate the output of the units C and B and the control coils of the unit A, is used in the broad sense'bf that term, i. e., as opposed to alternating current and as including pulsating current such as produced by a generator or rectifier and not in the limited sense only of absolutely continuous, pulse-free-current such as produced'by a chemical cell under constant load.

As the description proceeds, it will become apparent that by appropriate construction of the unitB and by use or elimination of the unit C the invention may be employed to respond either or is of such magnitude f of a D; C. coil i6 serving as the control coil. All

-.4' unit or subcircuit and accomplishes control of the magnitude and the. sign of the output in accordance with the magnitude and sign of the signal without the employment of electron tubes. The unit A is the same in all 01' the circuitadisclosed herein and it will thus be described in detail but once in connection with the description of the circuit disclosed in Fig. 2. Referring to Fig. 2, the unit A comprises a pair of saturablereactors represented by the broken-line rectangles. i6 and IS. The saturable reactor I6 is composed of a pair of A. C. coils I1 and i6 and of the coils are wound on a common iron core in such manner that current flowing in the coils I1 and I6 will not induce current or volt age in the D. C. coil l9, while flux produced by direct current flowing in the D. C. coil I! will vary the impedance of the A. C. coils l1 and I6 by varying the degree of saturation of the core 20. The reactor is further so designed that the coils I1 and I8 have a very high impedance when no current is flowing in the D. C. coil [9. Necessarily the reactor and particularly the coils thereof must be designed with a view to the voltages with which it is to be employed, with the coils I! and I8 being capable of taking substantially the full applied voltage when no current is flow! ing in the D. C. coil lb. The saturable reactor to an A. C. or a D. C. input or control signal,

while obtaining either an A. C. or a D. C. output. Moreover, by the employment of A. C. or D. C. signal receiving units B of the character hereinafter described, circuits embodying the concept of this invention may be employed to obtain an A. C. output which is directly proportional in magnitude to the magnitude of the input signal regardless of whether that be an A. C. or a D. C. signal; and similarly a D. C. output may be obtained which also is proportional to the input signal regardless of whether the same is an A. C. or a D. C. signal. Equally important is the fact that the sign of the output, be it the A. C. output or the D. C. output, is also controlled by the sign of the input or control signal. The

- meaning of the term sign" as applied to D. C. signals or output is, of course, the customary meaning and hence will be understood. The meaning of the term sign as applied to an A. C. signal or output is that of 180 phase displacement. Thus' circuits embodying the concept of this invention may be employed as D. C. amplifiers, as amplifiers and converters of A. C. signals to D. C. signals, as means for controlling A. C.

output either by D. C. or A. C. signals, or, as

stated another way, as an amplifier of A. C. signals and as an amplifier and converter of D. C. signals into A C. signals or output.

Turning now to a consideration of the more detailed embodiments of the invention, the unit A, being the basic portion of this invention. will first be described. This unit, as already lstated, is the main amplification stage and control I6 is identical with the reactor is andcomprises A. C. coils 2| and 22 and a D. C. coil 23, all wound on a common iron core 24.

The unit A, hereinafter sometimes referred to as the saturable reactor circuit, is completed by an A. C. supply circuit comprising power supply leads 25 and 26 adapted to be connected to an A. C. power source represented at 21, and output leads 28 and 29 terminating in output terminals 30. The A. C. coils of the saturable reactors are so connected in the supply circuit that the output will have a sign depending upon which of the two reactors is predominating at when oneof the reactors is predominating the reactor is predominating the connection of the reversed, thereby bringing about the reversal in sign above mentioned. While this might be acoutput terminals 30 will be connected to the source 21 in one manner, while when the other output terminals 30 to the source 21 will Just be complis'hed in a variety of ways, the A. C. coils I1 and 2| have one end connected to the power lead 25 by leads 3! and 32, respectively; The coils i8 and 22 of the reactors l6 and i6, respectively, have one-end connected to the power lead 26 by leads 33 and 34, respectively. Theremaining ends of the coils I I and 2i are by leads I! and 36 connected, respectively,,to the output leads 28 and. 29, while the remaining ends oi coils l8 and 22 are by leads 3'! and 38 connected,

respectively, to the output leads 26 and 26. 'There results in effect a construction in which the coils ll, l8, 2i and 22 form the legs of a Wheatstone bridge with the power supply leads 25 and 26 being common to the coils l1 and 2i and i8 and 22, respectively, and with the output leads 26 and 29 in common to the coils I1 and 22 and i6 and 2i, respectively.

.In the embodiment of the invention shown in Fig. 2, the circuit is adapted to respond to a D. C. input or control signal. Accordingly, there operable toreceive a D. C. signal, amplity the same to a magnitude suitable for use in connection with the saturable reactors II and I3 and, at the same time, cause energization 01 one or the other, or both, of the D. C. windings i3 and 23, as may be desired. Herein the unit B is of such character that an input signal will cause energization of the D. C. windings l3 and 23, as shown. in Fig. 3, wherein'the line il represents the current flowing in the coil I 3 and i2 represents the current flowing in the coil 23. In other words, when the input signal is zero the coils l3 and 23 will each have the same current flowing therein with a value as represented by the crossingof the lines i I and 2 at the point 43. With an increase in the signal magnitude, the current in the coil i3 will increase, while the current in the coil 23 will decrease at the same -rate. Upon reversal of the sign of the signal and increase in magnitude, the current in the coil 23 will increase while the current in the'coil U will decrease again at the same rate;

While a unitB capable of producing currents in the coils l9 and 23 of the character described it next be assumed that the sign or polarity oi! the D. C. input signal is such that an increase in signal magnitude ialls to'the right oi the vertical axis of the graph of Fig. 3. Under those circumstances the current ii flowing in the D. C. coil I! will increase and the current i2 flowing in the coil 23 will decrease, such increaseand decrease being by equal amounts and proportional to the increase in signal input. With such increased flow of current in the coil IS, the impedance or the A. C. coils I1 and I3 associated therewith will decrease and there will be a correspondingly smaller voltage drop across those nected as here shown, there will be a diflerence might take a variety of forms, one such unit is shown in Fig. 2, it being understood that the showing is exemplary only and that a variety of other subcircuits might be employed and that, in particular, it might prove necessary to have more than one stageto produce the amplification of the signal required to provide direct currents of a magnitude suitable for control of saturable reactors. Herein the unit B or signal input circuit comprises a pair of electron tubes 43 and 44 each having a plate, a cathode l6 and a grid ll. The tube 43 has a plate circuit, generally designated 48, which includes the D. C. coil l3 of the saturable reactor l3 and the tube 44 has a plate circuit, generally designated 43,.which includes the D. C. coil 23 of the saturable reactor IS. A D. C. voltage source, herein shown as a battery 33 common to the two plate circuits 43 and 43, supplies the plate voltage of the tubes. Each of the tubes. 33 and M has a grid circuit, generally designated 3i and 32, respectively, with each circuit including a resistance 33 and a grid bias voltage source,here shown as a battery 54 oi. potential between the output terminals 33. The magnitude of this diflerence oi. potential between the output terminals 33 will vary proportionally with the D. C. input signal, for variation in the currents ii and i2 is proportional to the input signal as can readily be'seen from Fig. 3.

The absolute value oi the output of the saturable reactor circuit is, however, not limited by the absolute value of the input signal. On the .contrary, this absolute value of the output of the saturable reactor circuit will be determined by the character and size of the A. C. supply source 21.

It now it be assumed that the sign or polarity of the input signal is reversed and then increases in magnitude as before, it will be noted that just the opposite occurs, that is, that the current 12 flowing in the coil 23 increases, whereas the curdifference oi. potential between the output tercommon. to the two grid circuits. The D. C. signal input terminals 54 and 55 are connected to the not common ends of the resistances 33. As above indicated, the tubes 43 and N are normally so biased that at zero magnitude of input signal an equal current will flow in the plate circuits of the tubes. As the signal increases in magnitude from zero value, the current in the plate circuit oi one of the tubes will increase, while the current in the plate circuit of the other of the tubes will decrease proportionately depending upon the sign or polarity of the input signal. g a

For ready understanding of this invention, the operation of the circuit as thus far described will circuit having, 'as best seen in Fig. 4, an alternating current output represented by the line 33 which is proportional in magnitude to the magnitude of a D. C. input signal and which corresponds in sign to the sign or polarity of the D. C.

input signal. Thus the circuit of Fig. 2 so far described gives control by means of a D. C. signal over the power supplied to a single phase now be set forth. Let it be assumed, therefore.

that the input signal is zero. Under this assumption, the direct current flowing in the coils l3 and 23 will be equal and, while such flow of current in the windings l9 and 23 will serve to reduce the impedance oi. the A. C. coils of the saturable reactors, nevertheless, there will be no diflerence in potential across the output terminals 33 o! the A. C. load, with the control governing not only the magnitude but also the phase or sign of the A. C. power supplied, and with the magnitude of the supply proportional to the magnitude of the D. C. signal. In this connection, it is also pointed out that, with the A. C. coils of the saturable reactors so connected as to' prevent their inducing any voltage in the associated D. C. coil, the saturable reactor circuit is incapable of influencing the signal input circuit and thus reactions of the controlled signal, that is', the' output of the saturable reactor circuit, be it of a character to be classified as a signal, or be it the actual power supplied to a load, such as a motor or the like, cannot be reflected back into the signal input circuit.

' In the embodiment oi the invention shown in Fig. 2. the unit C is connected as the A. C. load of the saturable reactor 'circuit. Herein. as'

' already stated, the unit C is a rectifier and,'as a result of the employment of a rectifier which gives full wave rectified output, a circuit results which is in effect a direct current amplifier. Herein the rectifier unit C is composed oi-iour grid controlled, gaseous tubestii, 8|, and 88, each having a plate 64, a cathode 85 and a grid 66. The rectifier is inductively coupled to the saturable reactor circuit through the medium oi a transformer T having a primary winding ll connected to the output terminals '30 and a secondary'winding. 68. The tubes 80 to 83 are connected to operate in pairs, depending upon the polarity of the output oi the saturable reactor circuit. .To that end, the plates 84 of the tubes. 60 and iii are by leads-8a and Ill, respectively, connected to the ends of the secondary winding 68, while the cathodes 65 of the tubes 82 and N are by the same leads connected to the ends of the secondary winding 68. The cathodes 65 01' the tubes 60 and Si in turn and the'plates 64 01 the tubes 62 and 63 are by a common lead Ii connected to a center-tap 12 of thesecondary winding 68. The lead ll actually, of course, is a split lead incorporating therein output terminals 13 to which a D. C. load is intended to be connected. The grid voltages are designed to be either in phase or in counterphase' with the output of the saturable reactor circuitfso that one or the other oi the pairs of tubes may function, depending upon the sign or phase of the output of the saturable reactor circuit. Accordingly, the grids 66 of the tubes 60 andti are by leads/l! and 15; respectively, connected to the ends of a secondary winding 16o! a transformer 11 having a primarywinding 18 adapted to be connected to a suitable A. C. source represented at 19. The midpoint of the secondary winding 16 is by a' lead 80 connected to the common lead ll. Potential for the grids 66 of the tubes 82 and 83 is provided respectively by windings 8| and 82 con.- stitutinga. split secondary of a transformer 83 havlnga primary winding 84 connected to a suitable A. C. source represented at 85. The remain! ing ends of the windings 8i and 82 are connected.

respectively, to the leads 89 and 10. It is to be appreciated that, though not here shown, suit- I able heating elements are provided for cathodes oi! the tubes.

With a rectifier oi the character here disclosed. one of the tubes 60 to 63 will-fire during each half cycle of the alternating current output of the saturable reactor circuit. Tubes 60 and BI will the .fire, one for the positive, the other for the negative full half cycle when the output of the saturable reactor has one sign, while the tubes 62 and 63 will fire, one for the positive, the'other for the negative halt cycle when the output of the saturable reactor circuit is of reversed sign. Thus full wave rectified output is obtained at the output terminals 13 of the rectifier circuit. Since full wave rectified output is obtained, it will be proportional 'in magnitude to the magnitude of the output of the saturable reactor circuit and hence proportional to the magnitude of the input signal since the output of the saturable reactor circuit (see Fig. 4) was shown to be proportional to the input signal. Further, the D. C. output of the rectifier circuit will vary in polarity with the polarity of the input signal and thusthere results an output such as represented by the line 86 of Fig. 5, namely, a D. C. output which is proportional in magnitude to the magnitude oi the input signal and also corresponding in sign to the signoi the input signal.

The complete circuit of Fig. 2 lends itself to the employment of a negative feed-back, thereby assuring a stable and linear D. C. amplifier. To that end, a potentiometer, generally designated 81, is connected across the output terminals Ito! the rectifier circuit with the end terminal II, and the variable terminal or contact by leads it and 9|, respectively, connected into the input circuit intermediate the terminal BI and the resistance 8.3 in such manner as to serve as a negative icedback.

In Figs. 6 and '11, inclusive, there are disclosed embodiments of my invention in circuits responding to or controlled by an A. C. signal. Such circuits may have an A. C. output, as in Figs. 6 and 'l or may have a D. C. output, as in Fig. 8. Referring first to Figs. 6 and'7, the circuit therein 20 disclosed is composed of a saturable reactor circult A and an input signal amplifying and moditying unit or subcircuit B. The saturable reactor circuit or the unit A is identical with-the unit A shown in Fig. 2. Sumce it to say, there! M lore, that the unit A is composed of two saturable reactors l5 and i8 and that the reactor it has two. A. C. coils l1 and i8"and.a D C. coil i8", and that the reactor It has two A. .C. coils 2i and 22' and an C. coil 23". Completing the saturable reactor circuit is a supply circuit having power leads. 25' and 28' connected to a source of alternating current power, represented at 211, and output leads 28' and 29' connected to output terminals 3.0 The coils are connec as described in connection with Fig. 2. v

Unit B, the signal input circuit, like the unit 13,01 Fig. 2, is'adapted to receive the input or cbntrol signal, amplify it so as to convert 'it to value capable of use with saturable reactors, and modify or condition the signal for use with" saturable reactors and to accomplish the end here sought. Such modification in this form of the inventlon'involves conversion at the signal from A. C, to D. C. and iurther'involves modification to result in a signal oiappropriate character. Herein the unit -B' must besuch as to result in acurrent in the D. C. windings l9 and 2 of the character illustrated in Fig. 9. In other words ii il' represents the current flowing in the winding I9 and i2 represents the current flowing in the winding 23', the currents .in the wind-'- ings i9" and 23' at zero value of input signal must be equala'nd must have a value 'such as repre- 55 sentedby the'point It at which the line representing the current il and the line representing the current i2 cross in the graph of Fig. 9. It

will be seen from this figure that asthe signal increases in value from zero the current in one 60 of the DC. windings will increase, while the current in the other D. C. winding will decrease, the increase and. decrease being proportional'to one another and also proportional to the increase I in signal magnitude. Depending upon the sign of the input signal, one or the other of the coils l9 and 23' will have the current fiow therein increasedwhile the other will have the current fiowtherein decreased.

Shown in Fig. 7 for exemplary purposes only, it being understood that a variety of other circults might be employed and that, in particular, it might be necessary to provide more {than a single amplification stage, is one specific-embodiment. that the unit B" may take. As shownin 75 Fig. 7, unit B comprises a pair of electron tubes l! and I02, each having a plate i03,'a cathode IM and a grid I05. The tube i0l has a plate circuit, generally designated I06, having in series therein, in parallel with a condenser I01, the

cults of thetubes IN and I0! are completed by an A. C. voltage source, represented at H0, common to the two plate circuits and providing the plate voltage for the tubes. The grids I are connected to opposite ends of a winding Iii constituting the secondary winding of a transformer,

generally designated H2, having a primary windmg H3 connected at its ends to signal input terminals Ill and H5. The midpoint of the secondary winding III is by lead 8 connected to the juncture of the plate circuits with the cathodes. Though not here shown, it is'to be appreciated that the tubes IM and I02 are provided with suitable means for heating the cathodes I04.

The tubes are normally biased so that at zero signal magnitude there is flow of current in the of the character represented by the'line ill of Fig. 10, namely, an outputwhich is proportional in magnitude to th input signal and which, moreover, varies in sign with the sign of the input signal.

It will be seen from the foregoing that the circuit of Figs, 6 and 7 may be considered as an AIC. amplifier. To assure a stable 'and'linear A. ,0. power amplifier, a negative feed-back is preferably incorporated and the circuit of Figs. 6 and 7 lends itself admirably to this purpose. Accordingly, there is connected across the output terminals 30 a potentiometer, generally designated H8. The fixed terminal I i9 and the movable contact I of thispotentiometer are by leads Hi and I22, respectively, connected, into the input circuit intermediate the input terminal 5 and the primary winding I I in a manner to proplate circuit of the tubes and, moreover, this current is equal in the two plate circuits. With such bias and with the circuit arranged as here shown,

an increase in magnitude of the A. C. signal from zero value will result in an increase in the plate current of one of the tubes and a corresponding decrease in the plate current of the other tubes. Whether the plate current of the tube increases or decreases with an increase in signal value is determined by the sign of the A. C. input signal. i

A brief description of the operation of the circuit of Figs. 6 and '7 may facilitate understanding of the invention and appreciation of the advantages thereof. Let it be assumed, therefore,

' that the input signal is zero. Under that condition, there will flow in the D. C. coils i9 and 23' a direct current of the same value. While there is thus current flowing in the D. C. coils l9 and 23', with a resultant change in the impedance of the A. C. coils, there is no difference of potential. between the output terminals because the terminals '30, due to the'particular arrangement of the A. C. coils in the supply circuit, are connected to points in the circuit having the same potential. Let it be assumed further that the A. C. input signal is now increased from zero to somedefinite magnitude and that the sign of the input signal is such that the signal will lie to the right of the vertical axis of the graph of Fig. 9. Under that assumption, the current ii flowing in the D. C. winding I9 will increase,

while the current 12' flowing in the winding 23 will decrease. Hence the degree to which the cores of the saturable reactors l5 and iii are saturated with flux will be varied with a resultant change in the impedance of the A. C. windings of the reactor I 5 and the A. C. windings of the reactor It. This will, due to the manner of connection of the A. C. coils in the supply circult, produce a voltage differential between the output terminals 30'. Conversely, if the sign of the input signal is reversed and the signal then increased in magnitude as before, the current i2 flowing in the D. C. winding 23' will increase, while the current il' flowing in the winding l9' will decrease. Hence the voltage differential between the terminals 30 will be of the same value for the previous condition. It will be apparent, V

' input signal. To that end, a rectifier circuit or unit C is connected as the load of the saturable reactor circuit or unit A which, in turn, :is controlled by an input signal circuit or unit B, the latter two being the corresponding units of Figs. 6 and 7. The unit C is identical with the unit C of Fig. 4. Suffice it to say, therefore, that the rectifier C comprises four grid controlledl, gaseous electron tubes 602-61, 62 and 63', each tube having a plate 64', a cathode 65 and'a grid 68. The rectifier C is inductively coupled to the saturable reactor circuit A through the medium of a transformer T' having a primary winding 6'! connected to the output terminals 30 of the saturable reactor circuit and a secondary winding 68'. Plate voltages are obtained by connection of the plates of the tubes'60 to 63' to the ends of midpoints of the secondary winding 68', while grid voltages are obtained from suitable A. C. sources represented at 18' and 85' with the grid voltages either in phase or in counterphase with the output of the saturable reactor circuit A. operate in pairs, one pair functioning when the output of the saturable reactor circuit is of one sign, the other pair functioning when the outputof the saturable reactor circuit is of reversed sign,

The tubes are so connected that they with one tube firing during each half cycle so as to obtain fullwave rectification.

With this full wave rectification, the D. 0.

the magnitude of the A. C. signal (see Fig. 10),

the D. C. or endoutput of the entire circuitwill also be proportional in magnitude to the A. C. input signal. Further, with the sign of the output of each unit corresponding and controlled by the sign of'the input to each unit, the D. C. or end output of the entire circuit willalso correspond to the sign of the A. C. input signal. Accordingly, there results an output of the character represented by the line 1230! Fig. 11. i

I claim as my invention:--

1. An electrical control circuit comprisingga signal input circuit having two ,sets of output terminals and operable to produce at aeaich s'etof output terminals a direct current which at 1 11 zero signal is equal at both sets 01' terminals and is \above zero in magnitude and upon increase in signal magnitude increases in magnitude at one set of terminals and decreases correspondingly at the other set of terminals, increase or decrease of the output current at a set of terminals being dependent upon the sign of the signal, a saturable reactor circuit comprising a pair of saturable reactors each having a pair of A. C. coils and a control coil wound on a common core, the A. C. coils being so arranged as not to induce an A. C. voltage in the associated control coil and said control coils being connected one to each set of output terminals of said input circuit, and a supply circuit for an A. C. load adapted for connection to a source of alternating current, the A. C. coils of said re actors being connected in the supply circuit to form with the load separate circuits each including the A. C. coils of one reactor reversely connecting the load in said supply circuit, and a iull wave rectifier circuit connected to form the load for said supply circuit and having output terminals for the connection of a D. C. load thereto, the output of said rectifier circuit varying in sign and magnitudewith the input signal.

2. An electrical control circuit comprising a signal input circuit having two sets of output terminals and operable to produce at each set of output terminals a direct current which at zero signal is equal at both sets of terminals'and is above zero in magnitude and upon increase in signal magnitude increases in magnitude at one set of terminals and decreases, correspondingly at the other set of. terminals, increase or decrease of the output current at a set of terminals being dependent upon the sign of the signal, a saturable reactor circuit comprising a pair of saturable reactors each having a pair of A. C. coils and a control coil wound on a common core, the A. C. coils being so arranged as not to induce an A. C. voltage in the associated control coil and said output terminals of said input circuit, and a supply circuit for an A. C. load adapted for connection to 'a source of alternating current, the tour A. C. coils of said reactors being connected in the supply circuit in a manner such that each forms one leg oi. a Wheatstone bridge, and that the A. C. coils of each reactor form diametrically opposed legs of the bridge, and a full wave rectifier circuit connected to form the load for said supply circuit and having output terminals for the connection of a D. C. load thereto, the output of said rectifier circuit varying in sign and magnitude with the input signal.

3. An electrical control circuit comprising a signal input circuit having two sets of output terminals and operable to produce at each set ofoutput terminals a direct current which at zero signal is equal. at both sets of terminals and is above zero in magnitude and upon increase in signal magnitude increases in magnitude at one set of terminals and decreases correspondingly at the other set of terminals, increase or decrease of the output current at a set of terminals being dependent upon. the sign of the signal. a saturable reactor circuit comprising a pair of saturable re-- actors each having a .pair of A. C. windings and a D. C. winding wound on a common core, the- A. C. windings being so arranged as not to induce an A. C. voltage in the associated D. C. winding and said D. C. windings being connected one to each set of output terminals of said input circuit, and a supply circuit for an A. 0. load ing current, the tour A. C. coils of said reactors being connected in the supply circuit in a manner such that each forms one leg of 9. Wheatstone bridge, and that the A. C. coils of each reactor are in series when there is an unbalance of the bridge, and a rectifier circuit comprisin aninductive coupling having a primary winding connected as the load in said supply circuit and a center-tapped secondary winding, two pairs of grid controlled, gaseous electron tubes, one pair of said tubes having its plates connected to the ends of said secondary wind- 8 and its cathodes connected to the centertap on said secondary, and the other pair having its plates connected to the center-tap and the cathodes connected to the ends of said secondary winding, and means providing grid voltages for saidtubes keeping the grid voltages of one pair of tubes in phase and the grid voltages is equal at both sets of terminals and is above zero in magnitude and upon increase in signal magnitude increases in magnitude at one set of terminals and decreases correspondingly at the other set oi terminals, increase or decrease of the output current at a set of terminals being dependent upon the sign of the signal, and a saturable reactor circuit comprising a pair 01' saturable reactors each having a pair of A. C. coils and a D. C. coil wound on a common core, the A. C. coils being so arranged asnot to induce an A. C.

voltage in the associated D. C. coils and said D. C.

coils being connected one to each'set of output terminals of said input circuit,'and a supply circuit for an A. C. load adapted for connection to control coils being connected one to each set of a source of alternating current, the four A. C.

coils of said reactors being connected in the sup f ply circuit in a manner such that each forms one leg of a Wheatstone bridge and that the A. C. coils of each reactor are connected in diametrically opposed legs of the bridge.

5. An electrical control circuit comprising a D. C. signal input circuit having two sets of output terminals and operable to produce at each set of output terminals'a direct current which at zero signal is equal at both sets of terminals and is above zero in magnitude, and upon increase in signal magnitude increases in magnitude at one set of terminals and decreases correspondingly at the other set of terminals, increase or decrease of the output current at a set oi terminals being dependent upon the sign of the signal, a saturable reactor circuit comprising a. pair of saturable reactors each having a pair of A. C. coils and a D. C. coil wound on a common core, the A. C. coils being so arranged as not to induce an A. C. voltage in the associated D.=C. coil and said D. C. coils being connected one to each set or output terminals of said input circuit, and

a supply circuit for 'an-A. C. load adapted for connection to a source of alternating current, the A. C. coils of said reactors being connected in the supply circuit to form with the load separate cir cuits each including the A. C. coils Of one reactor reversely connecting the load in said supply circuit, and a full wave rectifier circuit connected to form the load for said supply circuit,

' the output of said rectifier circuit varying in signand magnitude with the D. C. input signal.

i set or output terminals 9. direct current which at zero signal is equal at both sets of terminals and is above zero in magnitude, and upon increase in signal magnitude increases in magnitude at one set of terminals anddecreases correspondingly at the other set of terminals, increas or decrease of the output current at a set of terminals being dependent upon the sign of the signal, a saturable reactor circuit comprising a pair or saturable reactors each having a pair of A. C. coils and a D. C. coil wound on a common core, the A. C. coils being "so arranged as not to induce an A. C. voltage: in the associated D. C. coil and said D. C. coils being connected one to each set of output terminals of I said input circuit, and a supply circuit for an A. C. load adapted for connection to a source of alternating current, the A. C. coils of said reactors being connected in the supply circuit to form with the load separate circuits each including the A. C. coils of one reactor reversely connecting the load in said supply circuit, a full wave rectifier circuit connected toform the loadi'or said supply circuit, the output of said rectifier circuit varying in sign and magnitude with the D. C. input signal, and a negative feed-back from said rectifier circuit to said input circuit. I

7. In an electrical control circuit, an A. C. signal input circuit having two sets or output terminals and operable to produce at each set of output terminals 9. direct current which at zero signal is equal at both sets of terminals and is above zero in magnitude and upon increase in signal magnitude increases in magnitude at one set of terminals and decreases correspondingly at the other set of terminals, increase or decrease of the output current at a set of terminals being dependent upon the sign of the signal, and a saturable reactor circuit compris ing a pair of saturable reactors each having an A. C. coil and a D. C. coil, said D. C. coils being connected one to each set of output terminals or said input circuit, and a supply circuit ior an.

A. C. load adapted for connection to a source of alternating current, the A. C. coils of said reactors being connected in the supply circuit to produce in a load connected to the supply circuit an alternating current varying in sign and mag nitude with the input signal.

8. In an electrical control circuit, an A. C. signal input circuit having two sets of output terminals and operable to produce at each set of output terminals a direct current which at' zero signal is equal at both sets of terminals and is above zero in magnitude and upon increase in a signal magnitude increases in magnitude at one set of terminals and decreases correspondingly at the other set of terminals, increase or decrease of the output current at a set of terminals being dependent upon the sign of the signal, and a saturable reactor circuit comprising a pair of saturable reactors each having a pair of A. C.

coils and a D. C. coil wound on a common core;

the A. C. coils being so arranged as not to induce an A. C.--voltage in the associated D. C. coil and said D. C. coils being connected one to each set of output terminals or said input cir cult, and a supply circuit for an A. C. load adapted for connection to a source or alternating current, the A. C. coils of said reactors being connected in the supply circuit to form with the load separate circuits each including the A. C.

the other set of terminals, increase or decrease of I the output current at 'a set of terminals being dependent upon the sign of the signal, a saturable reactor circuit comprising a pair of saturable reactors each having a pair of A. C. coils, and a D. C. coil wound on a common core, the A. C. coils being so arranged as not to induce an A. C. voltage in the associated D. C. coil and said D. C. coils being connected one to each set of output terminals of said input circuit, and a supply circuit for an A. C. load adapted. for connection to a source of alternating current, the A. C. coils of said reactors being connected in the supply circuit to form with th load separate circuits each including the A. C. coils of one reactor reversely connecting the load in said supply circuit, and a negative reed-back from the output of said saturable reactor circuit to said signal input circuit.

10. An electrical control circuit comprising an A. C. signal input circuit having two sets of output terminals and operable to produce at each set of output terminals a direct current which at zero signal is equal at both sets of terminals and is above zero in magnitude and upon increase in signal magnitud increases in magnitude at one set of terminals and decreases corresponding- 1y at the other set of terminals, increase or decrease of the output current at a set of terminals being dependent upon the sign of the signal, a

saturable reactor circuit comprising a pair of saturable reactors each having a pair of A. C. coils and a D. C. coil wound on a common core,

' the A. C. coils being so arranged as not to induce arate circuits each including the A. C. coils of one reactor reversely connecting the load in said supply circuit, and a full wave rectifier circuit connected to form the load for said supply cir-.

cuit, the D. C. output or said rectifier circuit varying in sign and magnitude with the sign and magnitude of the A. C. input signal.

11. An electrical control circuit comprising an A. C. signal input circuit having two sets of output terminals and operable to produce at each set of output terminals a direct current which at zero signal is equal at both sets of terminals and is above zero in magnitude and upon increase in signal magnitude increases in magnitude at one set of terminals and decreases correspond ingly at the other set of terminals, increase or decrease of the output current at a set of terminals being dependent upon the sign of the signaLa saturable reactor circuit comprising a pair of saturable reactors each having a pair of A. C. windings and a D. C. winding wound on a common core, the A. C. windings being so arranged as not to induce an A. C. voltage in the associated D. C, winding and said D. C. windings i being connected one to each set of outputterminals of said input circuit, and a supply circuit for an A. C. load adapted for connection to a' source oi alternating current, the A. C. coils of each reactor being connected in the supply circuit to function in series with each other and with a load connected in the supply circuit and in eflect in parallel with the A. C. coils oi the other of said reactors, and a rectifier circuit comprising an inductive coupling having a primary winding connected as the load in said supply circuit and a center-tapped secondary winding,

two pairs oi grid controlled, gaseous electron tubes, one pair of said tubes having its plates connected to the ends of said secondary winding and its cathodes connectedto the center-tap on said secondary and the other pair having its plates connected to the center-tap and its cathodes connected to the ends of said secondary grid controlled electron tubes each having a plate,

a cathode and a grid, a plate circuit for each 01' said tubes including a common A. C. source of-iplate potential and an inductively coupled sig'nal input means having a primary winding adapted for series connection with a signal source and a secondary winding connected at its ends to the grids of said tubes and at its midpoint to the cathodes of said tubes to complete grid circuits for said tubes, said tubes being biased to have current and equal current flowing therein at zero signal magnitude, a saturable reactor circuit comprising a pair of saturable reactors.

each having a pair of A. C. windings and a D. C. winding wound on a common core, the A. C.

I in

plates connected to the ends windings being so arranged as not to induce an A. C. voltage in theassociated D. C. winding and saidD. C. windings being electrically associated one with the plate circuit of each of said tubes, and a supply circuit for an A. 0. load adapted for connection to a source of alternating current, the A. C. coils oi each reactor beingconnected the supply circuit to function in series with each other and with a load connected in the supply circuit and in eil'ect in parallel with the A. C. coils of the other reactor, and a rectifier circuit comprising an inductive coupling having a primary winding connected as the load in said supply circuit and a center-tapped secondary winding, two pairs of grid controlled, gaseous electron tubes, one pair of said tubes having its of said secondary winding and its cathodes connected to the centertap on said secondary and the other pair having its plates connected to the center-tap and its cathodes connected to the ends of said secondary winding, and means providing grid voltages for said tubes keeping the grid voltages of one pair of tubes in phase and the gridvoltages of the other pair of tubes infcounterphase with their respective plate voltages.

- PAUL GLASS.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Willis Mar. 17, 1942 

